SmartAlarm Instruction Manual Rev 2
Page 105 of 115
Typical Example of Message Format
To read all contact status data on a 24 way SmartAlarm the following
message format has to be repeated 3 times, once for each alarm card node
address.
RTU
ADDRESS
FUNCTION
REGISTER
ADDRESS
No Of
REGISTERS
ERROR
CHECK
01
01
00 01
00 08
6C 0C
Example shows message for first card, Comms address offset 0.
Read Status
– Function 03 – Read Request – Master
Register Address
This is used to address the “start” channel to be read, typically the first
channel
“channel 1” contact status on alarm card would be register address
40001
To read the contact status registers use address range 40001- 40008
To read the alarm status registers use address range 40011- 40018
To read the disable status registers use address range 40021- 40028
Number of Registers
This represents the number of registers (Channels) the master wishes to
read. The range is 1- 8.
Read Status
– Function 03 – Read Response - Slave
Byte Count
This represents the number of bytes sent
Data
Data returned depends on register address originally specified by the master.
Register address 40001 - 40008 returns Contact status data
0 = Normal
1 = Abnormal
Register address 40011 - 40018 returns Alarm status data
64
Alarm Event return to normal
65
Subsequent Alarm Event activated
66
First-up Alarm Event activated
67
Subsequent Alarm Event Acknowledged
68
First-up Alarm Event Acknowledged
69
Alarm Event Ring-back
